The Brn-3b POU domain transcription factor is elevated in a significant proportion of breast cancers and in neuroblastoma tumours, where it is associated with increased proliferation, anchorage-independent growth, faster and larger tumour growth in xenograft models, resistance to growth inhibitory stimuli and increased migratory potential. These effects are associated with the ability of Brn-3b to regulate specific genes associated with these processes. Reducing Brn-3b can reverse many of these effects, suggesting that it may be possible to alter the growth and behaviour of tumour cells by abrogating Brn-3b in these cancers. This review discusses the effect of altering Brn-3b in these cancer cells and possible approaches to targeting Brn-3b as a strategy for therapy in treatment of breast cancers.